Abstract The phase space manipulation of bunched beams offers a wide range of flexibility in beam dynamics control for advanced accelerator application. In particular, the capability of exchanging the transverse and longitudinal phase spaces enables to switch the transverse and horizontal emittance or shaping the charge distribution of an electron bunch to improve acceleration gradient and transformer ratio in beam-driven accelerators. A deflecting mode cavity has been used as the most integral element in the beam control scheme as imposing a kick on particles transferred between the two phase planes. In practice, the presence of the RF element with a finite length, however, induces thick lens effect limiting the phase-space exchange (PSEX) performance based off a thin lens model. Extending the idea from [A. Zholents PAC 11], we proposed momentum compensation technique using a single accelerating mode cavity coaxially coupled with the deflecting mode one. This paper describes the composite 3.9 GHz system and presents design analysis, including tracking and particlein-cell (PIC) simulations, and layout of feasible experiment at the Advanced Superconducting Test Area (ASTA) of Fermilab
